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Does FreeBSD support power management on my laptop?
FreeBSD supports the <acronym>ACPI</acronym> features found in modern hardware. Further information can be found in <citerefentry><refentrytitle>acpi</refentrytitle><manvolnum>4</manvolnum></citerefentry>.
Troubleshooting
Why is FreeBSD finding the wrong amount of memory on <trademark>i386</trademark> hardware?
The most likely reason is the difference between physical memory addresses and virtual addresses.
The convention for most PC hardware is to use the memory area between 3.5 GB and 4 GB for a special purpose (usually for PCI). This address space is used to access PCI hardware. As a result real, physical memory cannot be accessed by that address space.
What happens to the memory that should appear in that location is hardware dependent. Unfortunately, some hardware does nothing and the ability to use that last 500 MB of RAM is entirely lost.
Luckily, most hardware remaps the memory to a higher location so that it can still be used. However, this can cause some confusion when watching the boot messages.
On a 32-bit version of FreeBSD, the memory appears lost, since it will be remapped above 4 GB, which a 32-bit kernel is unable to access. In this case, the solution is to build a PAE enabled kernel. See the entry on memory limits for more information.
On a 64-bit version of FreeBSD, or when running a PAE-enabled kernel, FreeBSD will correctly detect and remap the memory so it is usable. During boot, however, it may seem as if FreeBSD is detecting more memory than the system really has, due to the described remapping. This is normal and the available memory will be corrected as the boot process completes.
Why do my programs occasionally die with <errorname>Signal 11</errorname> errors?
Signal 11 errors are caused when a process has attempted to access memory which the operating system has not granted it access to. If something like this is happening at seemingly random intervals, start investigating the cause.
These problems can usually be attributed to either:
If the problem is occurring only in a specific custom application, it is probably a bug in the code.
If it is a problem with part of the base FreeBSD system, it may also be buggy code, but more often than not these problems are found and fixed long before us general <acronym>FAQ</acronym> readers get to use these bits of code (that is what -CURRENT is for).
It is probably not a FreeBSD bug if the problem occurs compiling a program, but the activity that the compiler is carrying out changes each time.
For example, if <command>make buildworld</command> fails while trying to compile <filename>ls.c</filename> into <filename>ls.o</filename> and, when run again, it fails in the same place, this is a broken build. Try updating source and try again. If the compile fails elsewhere, it is almost certainly due to hardware.
In the first case, use a debugger such as <citerefentry><refentrytitle>gdb</refentrytitle><manvolnum>1</manvolnum></citerefentry> to find the point in the program which is attempting to access a bogus address and fix it.
In the second case, verify which piece of hardware is at fault.
Common causes of this include:
The hard disks might be overheating: Check that the fans are still working, as the disk and other hardware might be overheating.
The processor running is overheating: This might be because the processor has been overclocked, or the fan on the processor might have died. In either case, ensure that the hardware is running at what it is specified to run at, at least while trying to solve this problem. If it is not, clock it back to the default settings.)
Regarding overclocking, it is far cheaper to have a slow system than a fried system that needs replacing! Also the community is not sympathetic to problems on overclocked systems.
Dodgy memory: if multiple memory SIMMS/DIMMS are installed, pull them all out and try running the machine with each SIMM or DIMM individually to narrow the problem down to either the problematic DIMM/SIMM or perhaps even a combination.
Over-optimistic motherboard settings: the BIOS settings, and some motherboard jumpers, provide options to set various timings. The defaults are often sufficient, but sometimes setting the wait states on RAM too low, or setting the <quote>RAM Speed: Turbo</quote> option will cause strange behavior. A possible idea is to set to BIOS defaults, after noting the current settings first.
Unclean or insufficient power to the motherboard. Remove any unused I/O boards, hard disks, or CD-ROMs, or disconnect the power cable from them, to see if the power supply can manage a smaller load. Or try another power supply, preferably one with a little more power. For instance, if the current power supply is rated at 250 Watts, try one rated at 300 Watts.
Read the section on <link linkend="signal11">Signal 11</link> for a further explanation and a discussion on how memory testing software or hardware can still pass faulty memory. There is an extensive <acronym>FAQ</acronym> on this at <link xlink:href="http://www.bitwizard.nl/sig11/">the SIG11 problem <acronym>FAQ</acronym></link>.
Finally, if none of this has helped, it is possibly a bug in FreeBSD. Follow <link linkend="access-pr">these instructions</link> to send a problem report.
My system crashes with either <errorname>Fatal trap 12: page fault in kernel mode</errorname>, or <errorname>panic:</errorname>, and spits out a bunch of information. What should I do?
The FreeBSD developers are interested in these errors, but need more information than just the error message. Copy the full crash message. Then consult the <acronym>FAQ</acronym> section on <link linkend="kernel-panic-troubleshooting">kernel panics</link>, build a debugging kernel, and get a backtrace. This might sound difficult, but does not require any programming skills. Just follow the instructions.
What is the meaning of the error <errorname>maxproc limit exceeded by uid %i, please see tuning(7) and login.conf(5)</errorname>?

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Source string comment
(itstool) path: answer/para
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read-only
Source string location
book.translate.xml:1793
String age
a year ago
Source string age
a year ago
Translation file
books/faq.pot, string 296